🐍 Basics of Python : Syntax, Data Types, Type Casting, Variables, Operators, and More!

Python is known for its simplicity and readability, making it an ideal choice for beginners. In this post, we’ll go through fundamental Python concepts, including data types, variable scope, operators, and a few hands-on examples. If you're just starting out or need a refresher, this guide will get you up to speed!

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📝 Python Syntax and Basics

Python has a unique syntax that makes code easy to read. Here are some essential points:

• Case Sensitivity: Python is case-sensitive, so Name and name are considered different variables.

• New Statements: Each statement starts on a new line, making the code easy to follow.

Example:

x = 2
y = 3.14
name = "Krishna"
is_active = True

With Python’s print() function, you can display multiple values in a formatted way:

print("The value of x is {}, y is {}, name is {}, active status is {}".format(x, y, name, is_active))

# Using f-strings
print(f"The value of x is {x}, y is {y}, name is {name}, active status is {is_active}")

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🔍 Data Types in Python

Python supports several basic data types, such as:

• int (integer)

• float (floating-point number)

• str (string)

• bool (boolean)

Example:

x = 2
y = 3.14
name = "Krishna"
is_active = True

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🔄 Type Casting

Type casting allows you to convert one data type to another, which is essential when dealing with different data formats. Here’s how it’s done in Python:

x = 2
y = float(x)  # Converts int to float
print(y)  # Output: 2.0

c = 3.14
d = int(c)  # Converts float to int
print(d)  # Output: 3

x = "123"
f = int(x)  # Converts str to int
print(f)  # Output: 123

x = 123
s = str(x)  # Converts int to str
print(s)  # Output: '123'

x = "True"
y = bool(x)  # Converts str to bool
print(y)  # Output: True

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🔍 Type Checking

To check a variable's type, use the type() function, or verify a specific type with isinstance():

a = "True"
x = 4
y = 3.144
z = True

print(type(x))  # Output: <class 'int'>
print(type(y))  # Output: <class 'float'>
print(type(a))  # Output: <class 'str'>
print(type(z))  # Output: <class 'bool'>

# Using isinstance
print(isinstance(x, float))  # Output: False
print(isinstance(x, int))    # Output: True

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🌐 Scope of Variables in Python

In Python, the scope of a variable refers to where in the code that variable is accessible. Understanding scope is essential to managing variables and avoiding unintended changes to data.

Global vs. Local Scope

1. Global Scope: Variables declared outside any function are accessible throughout the code, from any function or code block.

    codegreeting = "Hello"  # Global variable
   
    def say_hello():
        print(greeting)  # Accessing global variable
   
    say_hello()  # Output: Hello
   

2. Local Scope: Variables declared within a function are only accessible within that function. These are known as local variables.

    codedef greet():
        greeting = "Welcome"  # 'greeting' is a local variable
        print(greeting)       # This works fine inside the function
   
    greet()           # Output: Welcome
    print(greeting)   # Raises an error because 'greeting' is not accessible globally
   

In the example above, the greeting variable is defined inside the greet() function, so it’s only accessible within that function. Trying to access greeting outside of greet() will raise a NameError since it doesn’t exist in the global scope.

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🧮 Operators in Python

Python offers several types of operators, including arithmetic, comparison, and logical operators.

Arithmetic Operators

Perform basic math operations like addition, subtraction, multiplication, and division.

a = 4
b = 5

print(a + b)  # Output: 9
print(a - b)  # Output: -1
print(a * b)  # Output: 20
print(a / b)  # Output: 0.8
print(a % b)  # Output: 4
print(b ** a) # Output: 625 (b raised to the power of a)

Comparison Operators

Comparison operators allow you to compare values:

result1 = (a == b)  # Output: False
result2 = (a != b)  # Output: True
result3 = (a > b)   # Output: False
result4 = (a < b)   # Output: True
result5 = (a >= b)  # Output: False
result6 = (a <= b)  # Output: True

print(result1, result2, result3, result4, result5, result6)

Logical Operators

Logical operators like and, or, and not help in combining conditions:

print((a > b) and (a < b))  # Output: False
print((a > b) or (a < b))   # Output: True
print(not (a > b))          # Output: True

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🎉 Real-World Examples

Let's look at two examples using these basics.

1. Discount Calculator

Calculate the discount amount and final price:

original_price = 120.0
discounted_price = 20

discount_amt = (original_price * discounted_price) / 100
final_amt = original_price - discount_amt

print(f"Original price: {original_price}")
print(f"Discount amount: {discount_amt}")
print(f"Final amount: {final_amt}")

2. Age Validator (Voting Eligibility)

Check if a user is eligible to vote:

user_age = int(input("Enter your age: "))

if user_age >= 18:
    print("Eligible to vote")
else:
    print("Not eligible to vote")

3. Temperature Converter

Convert Celsius to Fahrenheit:

celsius = float(input("Enter temperature in Celsius: "))
fahrenheit = (celsius * 9/5) + 32
print(f"Temperature in Fahrenheit: {fahrenheit}")

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📌 Wrapping Up

With these Python basics, you’re ready to dive deeper into the language. Practice using these fundamental concepts, and soon you’ll be tackling more complex projects. Whether you're building simple scripts or exploring data science, Python will continue to be your go-to tool.